U.S. President Barack Obama welcomed the two surviving Apollo 11 astronauts to the White House yesterday (July 22) to celebrate the 45th anniversary of the first moon landing.

Neil Armstrong and Buzz Aldrin became the first humans to walk on the lunar surface on July 20, 1969, while their third crewmate, Michael Collins, orbited the moon in a command module. The three men splashed down safely in the Pacific Ocean four days later.

Armstrong died in 2012 at age 82, but his widow, Carol, joined Aldrin, 84, and Collins, 83, for a private meeting in the Oval Office.

In a rare gathering of all three Apollo 11 crewmembers, Buzz Aldrin, Michael Collins and Neil Armstrong met with President Obama in White House on July 20, 2009, the 40th anniversary of the Apollo 11 lunar landing.

Drawing on Armstrong's famous "one small step" line, Obama said in a statement after the visit that the three Apollo 11 astronauts "took the first small steps of our giant leap into the future." The president thanked his guests for "serving as advocates, role models and educators who've inspired generations of Americans — myself included — to dream bigger and reach higher."

At the time of the Apollo 11 mission, President Richard Nixon was in office and Obama was only seven years old. After his last meeting with the crew — marking the 40th anniversary, in 2009, when Armstrong was still alive — Obama said he remembered following the Apollo missions, sitting on his grandfather's shoulders to watch the capsules coming into port in Hawaii.

NASA Administrator Charles Bolden was present during yesterday's meeting. Obama said that the space agency, under Bolden's leadership, is building on the legacy of the Apollo program "by preparing for the next giant leap in human exploration — including the first visits of men and women to deep space, to an asteroid, and someday to the surface of Mars."